Non partisan League of Nations Committee of D.C.
On November 19,1920 the US Senate voted 53-38 against the Versailles Treaty. Approval would have resulted in American participation in the League of Nations. This participation was opposed by many as an infringement of American sovereignty..
President Wilson's crowning achievement, in his mind, was convincing the world's leaders to create the League of Nations as part of the settlement of World War I. The critical element, according to Wilson, was Article Ten, which pledged all members of the League to respect and preserve the independence of all nations against external aggression. This was the principle of collective security and would prove the center of most criticism of the treaty.
American opposition to the League of Nations was divided between those who opposed any involvement with the League and those who had reservations about collective security. Those fighting any involvement were led by Senator Borah, who was an overt isolationist. The Republican majority leader, Senator Lodge, stated that he would support the treaty if Wilson would agree to what became known as the "Lodge Reservation." This stated that only the Senate of the United States could commit the United States to defend another country's independence. This struck at the heart of collective security.
Wilson refused to compromise, and the treaty was rejected. The lack of American support and participation doomed the League to become an ineffective organization.